Looking for input on frame design

[Jonnythecanuck]

Good Day everyone. My Name is Jon and I'm from Nova Scotia, Canada.

I am looking to start building my frame for a 5'x9' teardrop and would love some feedback from you experts.

My goals are:

a) Design and build my own custom trailer as used trailer prices are extremely high here in Nova Scotia.
b) Keep weight reasonable low (Well under my 2020 Rav4 Hybrid's 1750lbs towing capacity)
c) Ensure the frame is nice and strong and easily welded.

I am an industrial mechanic by trade and do have some welding experience. Last year I built a custom utility/zodiac trailer myself out of 3/16" angle with my AD/DC 240v buzzbox stick welder at home. 1/8" is the thinnest material I feel comfortable welding with a 7018 rod.

With that being said. I plan to cut/tack the frame together and have a professional welder MIG weld the frame. I then plan to weld on all secondary components such as floor and fender brackets myself.

I have spent a significant amount of time reading build journals here and have based the frame off of several I have seen here.

I have calculated the basic frame to be 139 lbs.

Any input would be greatly appreciated.









I hope you're able to see the dimensions and notes, I resided to 640x as the image upload page says that's the maximum size.

[saltydawg]

I would go with 2x3 14 gauge ( .085 ) its lighter by .3 lbs a foot and stronger. Yes it would be trickier to stick weld but it would not be bad to tack with a stick. It will allow you to drop about 10% of the weight, which I know it not much but its something. Also add a diagonal in the rear corners but try to plan it for your stabilizers at the same time.

Stick with the .120 center tongue thickness, and use the 14 gauge as the braces like you have it drawn now.

[pchast]

I would extend the center tow rail back at least one other cross member.
This would spread out the bending torque to the frame.

[twisted lines]

Looks Great as it is, consider angle iron between both spring perches and the frame, and tabs with holes to hold the flooring,
Maybe a dropped floor between your second and fourth cross,
some do that and it looks nice the few times its shown but it would be so much work

[tony.latham]

I think it's fine, other than maybe a little overkill using square tubing on the cross member above the axle. (But I'm not an engineer –-you must have a reason for that. )

As someone else said, add some tabs for cabin attachment. You might consider a removable coupler for security:





Tony

[Jonnythecanuck]

Wow, thanks for the quick and helpful input.

I do plan to add welded on floor brackets and potentially a 1-1/4" receiver for a bike. I will post my sketchup drawing as it progresses.

Tony, I have had your build journal bookmarked for a while now and was strongly influenced by your design . I find that removable coupler an excellent idea. Is there anything you would change in your design looking back on it?

Thanks again for the feedback, and happy new year!

[bobhenry]

If you intend to put the rack on the rear let your main tube run full length to the rear and you can add a bike rack or a platform directly into the "receiver" This addition also takes a bit of the stress off of the side rails .

[tony.latham]

Is there anything you would change in your design looking back on it?

There isn't. It evolved from the previous three builds and 17 years of teardropping.

Tony

[noseoil]

Looks good to me, but remember, when you weld the tongue assembly under the frame, weld the beads along the sides of the "A" frame. Don't weld the top edges of the tongue at the frame members, as it's plenty strong & the top edge of the tongue will weaken the tube due to heat distortion. I know his is being too picky, but the tongue is stronger this way, just sayin' it's a little better for metal fatigue in the long run. Welcome to the party!

[Jonnythecanuck]

Looks good to me, but remember, when you weld the tongue assembly under the frame, weld the beads along the sides of the "A" frame. Don't weld the top edges of the tongue at the frame members, as it's plenty strong & the top edge of the tongue will weaken the tube due to heat distortion. I know his is being too picky, but the tongue is stronger this way, just sayin' it's a little better for metal fatigue in the long run. Welcome to the party!

If I understand correctly, all tongue welds on the cross members should run front to back and not side to side? From my time in the welding shop when I was in trade school, I do remember being told that warpage happens in the direction of travel, so I imagine welding the tongue this way should keep transverse bowing of the cross members to a minimum.

At this point I have decided to trade my stick welder for a MIG and weld the trailer myself.